The scope of the examination is limited by Rule 95(2). The examining division is required to decide only whether the amended claims of the request constitute a limitation with respect to the claims as granted or amended (i.e. those referred to in D‑X, 4.2), and whether the amended claims comply with the requirements of Art. 84 and Art. 123(2) and Art. 123(3).
The term "limitation" is to be interpreted as meaning a reduction in the extent of protection conferred by the claims. Mere clarifications or changes made to protect a different subject ("aliud") are not to be considered as limitations.
More particularly, the limitation of a dependent claim only, without any independent claim being limited, is acceptable. However, it is not permissible to introduce non-limiting amendments in the description or in the claims that are not a consequence of the limitation of the claims (for example tidying up unclear claims, making amendments to improve the patent or cosmetic changes). Likewise, adding dependent claims in limitation is not permissible if not directly caused by the limitation introduced in the claims.
Amendments in a claim leading to a scope of protection which is smaller, but falls partly outside the extent of protection conferred by the claim previously on file, shouldmust be dealt with cautiously. Even if the amendment constitutes a limitation, such a claim would generally contravene Art. 123(3) (see also H‑V, 7 for Art. 123(3) in the case of a change of category of a claim).
For interpretation of Art. 84 and Art. 123(2), see F‑IV, 4, and H‑IV, 4.4. The description and drawings are used to interpret the claims in accordance with Art. 69(1) and its Protocol on Interpretation. Amendments made to these parts might therefore introduce matter contrary to Art. 123(3) (see H‑IV, 3.1 and H-IV, 3.3).
Errors of transcription or obvious mistakes can, however, be rectified on request or by the EPO of its own motion.
The filing of auxiliary requests together with a main request is possible (see H‑III, 3).